Belt Drive

[anthony goodson]

Okay i guess you are right. Another flex coupling and sliding spline would be unnecessary. Thrust bearing would be something like the aquadrive system correct? http://www.aquadrive.net

No you simply incorporate a deep groove angular thrust bearing into the cage on the end of the propeller shaft and make sure that it and the cage are anchored well enough to withstand the thrust from the prop. No need for any expensive or complicated parts. I am playing the devil's advocate here a bit ,and don't necessarily think this is the way to go as Frosty said "what's wrong with a gearbox." However if you are determined then this might help ,or at least be food for thought.

 

[anthony goodson]

Frosty they say that necessity is the mother of invention ,and the price of oil will shortly be that necessity. If they ever import one of these into the UK ,it will go straight into a museum. Petrol is now £1.35 a litre and rising ,diesel even worse.

 

[fpjeepy05]

Huge , inefficient push rod American dinosaur engine. when will America develop finesse in their engineering.

http://www.boats.com/blog/2011/02/seven-marine-reveals-557-hp-outboard-at-miami-boat-show/

557hp from 1000 pounds motor to prop. Pretty impressive if you ask me. Compared to the yamaha 350hp at 804lbs. Only applicable to boats that where running triples and quad 350s. How much does a 550hp diesel weight with strut, shaft, prop, tranny. All relative. I wouldnt want one or two but i know some people that will. Whats Thiland putting out these days?

 

[brian eiland]

7 Marine 557 Outboard

That is a picture of the new 7 Marine 557hp Outboard. This picture shows their "Propriety transfer case" which many are assuming to be a belt or chain. That is one heck of a belt haha.

If its a belt?, ...and I do suppose it is...my bet, it's a silent chain. It will be interesting to find out.

But then the manner in which it is configured down lower indicates the power must go thru two more 90 degree turns??

Eric Davis was asked how the engine’s power made the 90-degree change in direction to mate to a drive shaft, and he just shrugged and smiled. “I’ll have to explain that to you later,” he said. Apparently the Seven team is not ready to reveal all of its secrets.

We do know that shifting is accomplished above the gearcase. The gearcase has a four-inch-diameter tube – a standard size – but has twin pinion gears to transfer power from the vertical drive shaft to the horizontal prop shaft, while keeping the size of the case small and hydrodynamic.

 

[BMcF]

Finally found the details for the belt-drive splitter box we built. To reiterate..the input (center) was driven at 5500 RPM and 450 HP by a modified big block Ford V-8.

The box itself is all aluminum plate, both pinned and bolted at the edges.

Both output shafts were connected to Berkeley 12JG jets (aft) and a hydraulic pump and cooling water pump (fwd). Engine and jet connecting shafts were all cardan type.

 

[anthony goodson]

BMcF very simple and straightforward design just what I had expected to see. The fact that it runs jets ,gets over the reversing problem , and the need for thrust bearings .Thankyou for sharing that with us.

 

[fpjeepy05]

Finally found the details for the belt-drive splitter box we built. To reiterate..the input (center) was driven at 5500 RPM and 450 HP by a modified big block Ford V-8.

The box itself is all aluminum plate, both pinned and bolted at the edges.

Both output shafts were connected to Berkeley 12JG jets (aft) and a hydraulic pump and cooling water pump (fwd). Engine and jet connecting shafts were all cardan type.

Beautiful. I like it. Jets do make it simpler. What kind of belt was it again? And how well did it hold up? How much was it used?

Aside I found this

Its a 35hp Mud Motor. That uses a Good Year timing belt. W-1120. PDF Replacement Guide

Eagle Belts
They use that belt to transmit up to 50 hp in there products, and from what I've read not too many problems. Linear extrapolation puts the Eagle PD Red at about 145hp. So it doesn't seem too difficult for up to that kind of power. Anything more would get more and more difficult.

 

[BMcF]

Beautiful. I like it. Jets do make it simpler. What kind of belt was it again? And how well did it hold up? How much was it used?

.

We used Dayco (I think I earlier mispoke and said Gates..) RPP Synchro-Cog belts and pulleys. 85mm width, 14mm pitch.

Even though we 'erred' on the power side of the design in favor of keeping box weight and size minimal, we never saw any sign of wear..no 'belt dust'...never had to adjust belt tension over the 400 or so hours that we operated the test craft (a 13.5m hydrofoil).

A short duration..but with no indication of wear or problems, I would be quite confident to suggest that several thousand operating hours would be easily achieved...many more if it were not being operated at 5500 RPM all the time.

 

[nordvindcrew]

alternate drive systems

The late Rob White of Mississippi (?) built an atkin derived boat; the rescue minor. it used a friction drive and seemed to work well. perhaps hs son, who worked with him could help with details.

 

[BMcF]

Fun with belt drives.

Here is another one we built..twin jets in a 55' LOA catamaran unmanned RC model (SES actually) hull with a single Honda 18HP V-twin for power.

 

[brian eiland]

This belt drive subject has come again in relation to a new diesel engine outboard.
http://www.boatdesign.net/forums/outboards/new-diesel-outboard-53589.html

 

[FAST FRED]

How could you have a soft mount engine tensioning the belt?

Most car and truck engines are fitted with a spring powered belt tensioner.

Dozens to choose from at the parts counter OTS>

 

[brian eiland]

How could you have a soft mount engine tensioning the belt?

That's a good question Fred. It does require some extra thought in design and installation.

In the case that I brought up with this PYI unit I mentioned and photoed back HERE
the drive unit itself is an individual unit that is subsequently joined to the soft mounted engine by some sort of drive shaft with CV type joints.

Of course there were other units such as 'sail drives' that directly connected the engine to the drive train, and then soft mounted the whole unit into the hull with waterproof diaphrams.

 

[brian eiland]

Brian. Did you ever build the cat with counter rotating props driven by belts? I love that idea! Was the engineering done on the shafts ?
I did not get that built, nor did we go forward with the 'belt drive' concept.

There was no development monies available.

I had started out thinking Kevlar belts, but became convinced that the silent chain was a better idea. Here is a posting (2004) where I was going thru that transition:
YachtForums.Com - View Single Post - New Drive System from Volvo Penta

PYI had come out with a chain drive leg, but only marketed it for a few years. I'll see if I have a few other photos of it. I did collect a lot of info on these silent chains and identified a prime manufacturer I wished to work with on development of such an outdrive leg,...if some development monies should become available.

One sample installation I saved on my older computer
Paradise 60 :: Paradise Yachts

One older spec sheet on the smaller sized unit:

 

[FAST FRED]

IF I were planning on a belt drive I would attempt to put 2 spring belt tensioners working paired so the engine would not be pulled to one side by the tension..